by todofibraoptica

By Gilberto “GG” Guitarte

The year: 1998. The standard: ANSI-T1.413 Issue 2. The effect: the beginning of the end of the semi-eternal Copper Pair by the phone carriers.

ANSI-T1.413 Issue 2 ushered in the true revolution in residential Internet access over a twisted copper pair network commercially called “net surfing” or “web surfing” with —at that time— very respectable download speeds of up to 8 Mbps provided by DSLAMs (Digital Subscriber Line Access Multiplexers) in Central Office (CO). The scarce 640 Kbps of upload speed was more than enough to command internet searches for specific topics, and what was valued was the speed of download with the large amount of data/information previously requested by the user in a command of very few Bytes that required extremely low upload speed. We used to surf the web looking for information with simple short commands in Bytes and bps of upload, waiting on the web for an avalanche of data/information download of many Bytes and good speed in bps. Surfing the net is a completely asymmetric service; that is, the download speed is much higher than the upload speed, quite different from the symmetric service required by current applications to be able to work/study from home.

Later on there were improvements in download and upload speeds thanks to the evolution of standards that provided greater bandwidths at higher frequencies for both download and upload speeds; such as, ADSL2 and ADSL2+, giving rise to symmetric services made possible thanks to the variants of HDSL, SHDSL, HDSL2 and HDSL4, VDSL and VDSL2, up to—and including—G.fast (ITU-TG.9700 and G.9701).

The use of very high frequencies, on the order of 35 MHz in VDSL2 and up to 106 or 212 MHz in G.fast, required very short subscriber loop (or last mile twisted pair) distances; therefore, the DSLAMs were moved to the outside plant —requiring electrical power and air conditioning in those electronic cabinets now exposed to the environment. The copper loop had to be in optimal conditions in terms of insulation, shielding, and grounding, to mitigate the effect of noise or unwanted signals. The reality is that more than 90% of the telephone companies’ twisted copper pair installations were Cat 3 (up to 16 MHz) and required reliable and interference-free transmissions by X-TALK (NEXT and FEXT) at frequencies above their possibilities, it was too much to expect. More and more electronic noise mitigation measures had to be applied, such as the famous VECTORING, and attenuation reduction, such as, for example, further shortening the subscriber loop lengths to be able to use part of the existing copper last-mile network.

“THE END OF THE BEGINNING” (of Fiber in Residential Access Networks)

Until the late 1990s, residential fiber optic access networks (FTTH) were quite rare, awfully expensive, and Point to Point (P2P). In those networks, the CO optical transceivers (OLT or Optical Line Terminals), the outside plant fiber optic network (ODN or Optical Distribution Network), and the subscriber optical transceivers (ONTs or Optical Network Terminals), were dedicated elements for each user—the cost per user made them prohibitive. Their existence was made possible only due to strategic governmental decisions at the country level, such as was the case of Japan and South Korea.

PON networks (or Passive Optical Networks) began to develop at that time, which were P2MP (Point to Multi-Point) fiber-optic networks. In those networks, a passive element called the Optical Power Splitter (or splitter), allowed for both, the CO optical transceivers, as well as the primary network up to said splitter, to be shared by 32 or 64 users—drastically reducing the cost per user. Similarly, as the external plant between the OLT and ONT was fully passive (no need for electrical power) and glass (fiber optics), operating and maintenance expenses were drastically reduced as well!


Like the phone carriers, the cable companies tried (and continue to try today) to extend the life of the coaxial cable installed many years ago (several decades in many cases) in the last mile of their residential access networks. Just as the phone carriers made use of DSL technology, and its evolution, cable companies made use of DOCSIS (Data Over Cable Service Interface Specification) technology, and its evolution, going through DOCSIS 1.0, then 1.1, then 2.0, then 3.0, most recently 3.1, and finally—in the works right now—DOCSIS 4.0. Although the coaxial cable of the cable companies provided a superior bandwidth than the copper (Cat-3) twisted pair of the phone carriers, it also requires electrical power in the external plant at the node of transition of fiber to coaxial. Fiber runs from the Head End to the node. Finally, on the last mile of coax, conditioning of the shielded coaxial cable, and considerable maintenance are required to prevent egress of the transmitted signal and to mitigate the ingress of electromagnetic noise.


Having lived in Valencia for three years, I got used to the ADSL service offered by Spain’s Telefonica; so, when I returned to North Carolina in 2003, I subscribed to AT&T’s ADSL service by then available in my neighborhood. My upload and download speeds were—with good luck and good ambient temperature and humidity (and the time of day… let us never forget this factor)—of 800 kbps/100 kbps respectively. Already tired of the unpredictability of ADSL service due to the age of copper cables, in 2006 I switched to DOCSIS 2.0 service offered by TWC, my local cable company at the time.

My house was transformed into a piece of Gruyere Cheese—traversed from the outside in by coaxial cables to reach the various TV terminals. Internet service improved slightly, although its quality depended more than ever on the time of day since the signal—provided by the street’s coaxial cable—was in fact, shared bandwidth, with all users “hanging” on the same cable, coming from the same node … Uff!

I spent two years with TWC and reverted to AT&T, but now with a remote DSLAM located about 150 m from my house and with an ADSL2 + service that had more bandwidth than the previous one (ADSL) provided by that operator, and respectable digital TV service. All coaxial cables disappeared from my home; but, from the remote DSLAM to the old copper terminal box on the sidewalk—and the NID (or Network Interface Device) at my house—we still had to deal with “the old, deteriorated, poorly shielded, insulated copper cable; and, the old terminal box and its very outdated screw contact technology”. Given my permanent complaints, I was promoted to VDSL2 Service with two copper pairs dedicated to my home; but the aged cable—as well as the old terminal box—were still the weak link in the chain.


Just two years ago, tired of ATT showing up at my house every two or three months looking for pairs of copper in good condition between the street cabinet and my copper terminal box, and ready to cancel my contract with them once again, they told me: “For the same monthly cost of your current Triple-Play service, we can now migrate you to our new FTTH service, with 100Mbps!”

The Transition Process from Copper to FTTH at GG’s Home

  • Pedestals
    Old pedestals of telephone carrier (left) and cable company (right)

After enjoying a year without any issues with this service, they increased the cost; and, in response to my complaint, they told me that since I had been an exceptionally good customer for many years, they would keep the same monthly cost for me. Now, I am a VERY HAPPY USER of 1Gbps symmetric two-way service. Ah! and by the way… IT ALL RUNS ON FIBER OPTICS!

Gilberto “GG” Guitarte is an experienced fiber optics leader, former president of the Fiber to the Home Council Latin America Chapter (now known as The Fiber Broadband LATAM Chapter). Currently he’s a certified instructor by the Fiber Optic Association (FOA) and a consultant for Fiber Access Networks and Passive Optical LANs.


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